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Immunotactoid glomerulopathy with microtubular deposits, with reference to the characteristics of Japanese cases
M Fukuda1, K Morozumi, T Oikawa
1Department of Internal Medicine and Pathophysiology, Nagoya City University Graduate School of Medical Sciences, Japan. m-fukuda@med.nagoya-cu.ac.jp
Abstract:
We present the case of a 69-year-old man with nephrotic syndrome and renal insufficiency, who developed lobular glomerulonephritis. An electron microscopy examination of a renal biopsy showed microtubular structures of 24 nm in diameter in the subendothelial space and the paramesangial area. These deposits were PAS-positive and Congo red-negative, and revealed predominantly positive staining for kappa light chain. There was no evidence of diseases with highly organized glomerular deposits, such as amyloidosis, cryoglobulinemia, systemic lupus erythematosus or paraproteinemia. Therefore, the patient was diagnosed to have immunotactoid glomerulopathy (ITG). During a seven-year course he has not developed any disease known to be associated with organized glomerular immune deposits. Hence, we believe ITG occurred as a primary glomerular disease in this case. We also highlight cases of ITG with microtubular deposits that have been reported in Japan, compare these cases to previous reports, and show that the characteristics of the Japanese cases are male predominance; a high incidence of membranoproliferative glomerulonephritis (MPGN); a low incidence of monoclonal gammopathy and hematological malignancies and a higher incidence of hypocomplementemia.
Insights
This study details a rare case of primary immunotactoid glomerulopathy (ITG) presenting as lobular glomerulonephritis. The findings highlight unique characteristics of ITG, particularly microtubular deposits, in Japanese patients.
Area of Science:
- Nephrology
- Pathology
- Immunology
Background:
- Immunotactoid glomerulopathy (ITG) is a rare kidney disease characterized by the deposition of organized microtubular structures in the glomeruli.
- Distinguishing ITG from other glomerulonephritides with organized deposits, such as amyloidosis or cryoglobulinemia, is crucial for accurate diagnosis and management.
Observation:
- A 69-year-old man presented with nephrotic syndrome and renal insufficiency, diagnosed with lobular glomerulonephritis.
- Renal biopsy revealed subendothelial and paramesangial microtubular deposits (24 nm) that were PAS-positive, Congo red-negative, and kappa light chain predominant.
- No evidence of secondary causes like amyloidosis, cryoglobulinemia, lupus erythematosus, or paraproteinemia was found.
Findings:
- The patient was diagnosed with primary immunotactoid glomerulopathy (ITG) due to the absence of associated systemic diseases.
- Over a seven-year follow-up, no related conditions developed, supporting the primary nature of ITG in this case.
- Comparison with Japanese ITG cases revealed male predominance, high incidence of membranoproliferative glomerulonephritis (MPGN), low incidence of monoclonal gammopathy/hematological malignancies, and frequent hypocomplementemia.
Implications:
- This case expands the understanding of primary immunotactoid glomerulopathy (ITG) and its diverse presentations.
- The findings underscore the importance of electron microscopy and immunofluorescence in diagnosing ITG.
- Characterizing ITG in specific populations, like Japanese patients, aids in recognizing distinct epidemiological and clinical features.
